The entire disclosure of Japanese Patent Application No. 2007-300203 filed on Nov. 20, 2007, is expressly incorporated by reference herein.
1. Field of Invention
The present invention relates to a printer that has a cover that opens and closes to open and close a roll paper compartment or other part of the printer, and relates more particularly to a transportation roller pair for conveying roll paper or other print medium disposed therebetween, the transportation roller pair being disposed to the transportation path so that the rollers separate from each other when the cover opens.
2. Description of Related Art
Printers that print to roll paper or other type of continuous print medium, convey the paper by transportation roller pairs disposed to the transportation path, and have one roller in the transportation roller pair disposed to a cover that opens and closes so that the transportation path opens when the cover opens are known from the literature. Japanese Unexamined Patent Appl. Pub. JP-A-H06-40055, for example, teaches a thermal printer in which the transportation path opens when a cover is opened, enabling replacing the roll paper.
The rollers of the transportation roller pair are pressed together by a spring force so that the printing paper is held therebetween and can be conveyed with a predetermined transportation force. Therefore, when one roller in the transportation roller pair is disposed to an operable cover, a force (repulsion to the spring force of the transportation roller pair) urging the cover to open is always applied to the cover when the cover is closed. As a result, when the cover is unlocked and opened, the this force acting in the direction in which the cover opens may cause the cover to spring open quickly. Particularly in a printer on which the cover opens forward from an upright closed position to a horizontal open position, the weight of the cover combined with this spring force causes the cover to open with such force that it may forcefully impact the surface on which the printer is placed.